1. Technical Field
This disclosure relates generally to laser machining and, more particularly, to forming one or more apertures in a fiber-reinforced composite object with a laser.
2. Background Information
An aircraft propulsion system may include a nacelle with an inner fixed structure (IFS). This inner fixed structure may include two “clam-shell” halves. An upper side of each of these IFS halves may be pivotally attached to an engine pylon. Lower sides of the IFS halves may be connected together or to a divider by one or more latches.
The inner fixed structure is configured to form at least a portion of a bypass gas path between a fan section of the propulsion system and a bypass nozzle of the propulsion system. The inner fixed structure may also be configured to attenuate noise generated by the propulsion system and, more particularly, noised generated by the fan section. Each of the IFS halves, for example, may include one or more acoustic panels located along the bypass gas path. Each of these acoustic panels is typically provided with a plurality of internal chambers, which may be configured as resonators. An inner barrel of an inlet portion of the nacelle may also or alternatively include one or more of such acoustic panels. This inner barrel may form at least a portion of a gas path adjacent and/or through the fan section.
A typical acoustic panel includes a porous (e.g., a honeycomb) core bonded between opposing face sheets (e.g., skins). One of the face sheets is non-perforated. The other one of the face sheets, in contrast, is perforated with a plurality of through-holes. These through-holes provide pathways for sound waves to travel into the core for noise attenuation through, for example, Helmholtz resonance.
In a continuing effort to reduce propulsion system weight, at least the perforated face sheet may be constructed from of relatively light weight fiber-reinforced composite material. Forming through-holes in such a composite material, however, may be time consuming and expensive. In particular, a typical fiber-reinforced composite material may locally delaminate when subjected to heat generated by a typical rapid laser drilling process. Therefore, the through-holes in a fiber-reinforced composite face sheet are generally formed via mechanical drilling and/or media blasting.
There is a need in the art for improved processes for forming through-holes in a fiber-reinforced composite object.